Dennis Mahony

Dennis E. Mahony

Partner
Toronto: 416.865.8214
Fax 416.865.7380

Education

LLB, 1993
University of Toronto
BA, 1990
University of Calgary

Bar Admissions

Ontario, 1995

Overview

Dennis Mahony is the head of Torys’ Environmental, Health and Safety Practice, the Co-Chair of the firm's interdisciplinary Climate Change and Emissions Trading Practice and one of the core members of our Infrastructure and Energy Group.

He is certified by the Law Society of Upper Canada as a Specialist in Environmental Law and has been recognized over the years as one of Canada's leading practitioners, including in: Lexpert/ALM’s Canadian Legal Lexpert Directory; Practical Law Company’s Which Lawyer? Yearbook; Best Lawyers' Best Lawyers in Canada; Law Business Research’s International Who’s Who of Environment Lawyers; Legal Media Group's Expert Guides: Best of the Best; Legal Media Group’s Guide to the World’s Leading Environment Lawyers and Chambers & Partners (Band 1). Dennis is also a past recipient of the Lexpert award for Canada’s Top 40 Lawyers Under 40. He is a past Co-Chair of the International Outreach Task Force of the American Bar Association’s Section of Environment, Energy and Resources (SEER), the current International Vice-Chair of the Energy and Environmental Markets and Finance Committee of SEER, and a Past Chair of the Canadian Bar Association’s National Environmental, Energy and Resources Law Section.

Dennis' environmental, health and safety practice involves work with a broad range of public and private sector clients, including public and private companies, federal government agencies, Crown corporations, provincial bodies and municipalities. He provides advice to corporate clients in virtually every industrial sector, including renewable energy; pulp and paper; mining; chemicals and plastics; water and waste water treatment and disposal; manufacturing (including automotive, auto parts, adhesives, sports equipment, injection molding and food); financial institutions (including all of North America’s major banks); and real estate (including major property and property management corporations).

As part of his transactions practice, Dennis assists buyers, sellers, lenders and investors through all the environmental aspects of a transaction, from the design and coordination of deal-specific (often multiple-site, international) environmental liability assessments; through the negotiation of agreements; and in handling closing and post-closing details. In a typical year, the group is involved to varying degrees in more than 100 commercial transactions.

Dennis’ regulatory practice involves technical and strategic advice that spans the full range of issues in the environmental, health and safety field, including project development, particularly with respect to federal and provincial environmental assessments and other approvals; contaminated sites; quasi-criminal, civil and administrative liability assessments (including those related to government orders); transportation of dangerous goods and waste (domestically and internationally); climate change; general legal compliance; legislative initiatives; and Canada-U.S. cross-border issues.

Dennis' litigation related practice covers an equally broad range of issues, including environmental assessment and approval hearings, appeals of administrative orders, quasi-criminal defence work and civil litigation.

Torys' cross-border Climate Change and Emissions Trading Practice brings deep business law expertise to the many challenges and opportunities related to global warming. Understanding that the implications of the movement extends to every aspect of modern business, the group is interdisciplinary, drawing on a wealth of top-ranked expertise in a variety of fields, including energy and infrastructure; environmental, health and safety; corporate/commercial; securities; mergers and acquisitions; project finance; institutional lending; financial institutions; intellectual property; pension and employment; real estate and infrastructure; trade; tax; and litigation and dispute resolution.

Dennis’ climate change and emissions trading practice involves helping our clients navigate through this evolving, multi-faceted field, including keeping them informed on the numerous domestic and international developments in the area and working on project-specific teams for everything from assessing the ever evolving securities disclosure requirements to emissions trading.

Representative Work

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Recognition

Best Lawyers' Best Lawyers in Canada—Leading lawyer in insolvency and financial restructuring law (2010-2017)

Chambers & Partners’ Chambers Canada—Leading lawyer in Canada, environment (2016-2017)

The Legal 500 Canada—Leading lawyer in environment (2015-2016)

Chambers & Partners’ Chambers Global: World’s Leading Lawyers for Business, The Client’s Guide—Leading lawyer in environment (2014-2016)

Law Business Research’s Who’s Who Legal Canada—Leading lawyer in environment (2014-2015)

Lexpert/Thomson Reuters' Canadian Legal Lexpert Directory—Leading lawyer in environment (2014)

Insights

Media

Professional Involvement

Dennis is the former co-editor in chief of University of Toronto Faculty of Law Review. He is also an adjunct professor at the University of Toronto Faculty of Law, where he teaches Climate Change law. He regularly chairs and speaks at environmental, health and safety law conferences in Canada and the United States, and has authored and co-authored numerous articles.

Memberships and Affiliations

  • American Bar Association, Section of Environment, Energy and Resources (SEER), International Outreach Task Force (Co-chair)
  • American Bar Association, SEER, Energy and Environmental Markets and Finance Committee (2009/10 International Vice-Chair)
  • Canadian Bar Association, National Environment, Energy and Resources Law Section (2009/10 Immediate Past Chair)
  • Environmental Section, Ontario Bar Association (Executive)
  • International Bar Association
  • The American Society of International Law